Nikko is up in the mountains to the north of Tokyo and is famous for its temples and gardens. The royal family had a country retreat there and it is open to visitors. Use the train to get there. The station is in the high street and an easy stroll takes you to the main attractions, past numerous tourist shops and restaurants. I advise you not to take a car unless you go in midwinter. Finding a place to park can be a nightmare.
The natural scenery is magnificent. A huge, ornamental lake flows into a gorge down a waterfall that freezes in winter. Dress warmly if you go at that time of year. We visited Nikko in winter and spent most of our time huddled beside a fire in a restaurant overlooking the famous frozen waterfall. The mountains around the lake are covered in majestic trees. These tower above huge boulders and are an important feature of the temple gardens.
Don't forget your camera. You could spend an entire day taking photographs. The temples, royal holiday palace, lake, waterfall, sacred bridge and other attractions deserve your attention.